Enrichment of cancer cells is extremely significant in research and clinical aspects, and if cancer cells present in blood can be enriched, the enriched cancer cells can be applied to the diagnosis of cancer. For example, the most significant factor of a prognosis and a treatment of cancer is whether or not cancer cells have metastasized at the time of first medical examination or treatment. If cancer cells are spread to peripheral blood at an early stage, it is a useful method for determining disease progression of the cancer to detect circulating tumor cells (hereinafter sometimes referred to as the “CTCs”).
In a general cancer patient who has just started suffering from a metastasis, however, merely one CTC is present in his/her blood per ten billion blood cells. On the contrary, there are an overwhelmingly large number of blood components such as erythrocytes and leucocytes in blood. Accordingly, it is extremely difficult to enrich CTCs in a very low concentration so as to highly sensitively, highly efficiently and highly specifically analyze the CTCs. If the CTCs are enriched by a method using, for example, magnetic beads, density gradient centrifugation, a microchannel or a flow cytometer, it is necessary to perform a complicated treatment as well as the recovery rate is poor in some cases.
As another technique to segregate/enrich CTCs, a method using a polycarbonate filter has been proposed (see, for example, Non Patent Literatures 1 and 2). Furthermore, a technique to segregate/enrich CTCs by utilizing a difference in size has also been proposed (see, for example, Non Patent Literatures 3 to 5 and Patent Literature 1).
It is known that contact of blood with a surface of a medical material for an artificial heart-lung machine or the like causes an adverse reaction such as induction of thrombus formation or hemolysis due to activation of a complement system or activation of blood platelets. It has been reported that it is effective, for solving this problem, to coat a surface of a medical material with a prescribed compound (see, for example, Patent Literature 2).